In fabrication of semiconductor devices, a CMP process is used in planarization of an insulating layer or metal layer on a wafer surface or wafer. The CMP process is a process in which a polishing pad is placed on a polishing platen, followed by application of a hydrostatic pressure while a polishing head holds and rotates a wafer during rotation of the polishing platen, thereby planarizing a wafer surface layer through polishing using mechanical polishing action by the polishing pad and a polishing agent of a polishing slurry composition and chemical polishing action by an oxidant of the polishing slurry composition. The polishing slurry composition used in CMP may include a polishing agent of metal oxide particles, deionized (DI) water in which the polishing agent is suspended; an oxidant removing a metal oxide by forming a passive layer on a surface of a metal film; a corrosion inhibitor preventing excessive corrosion by passivation, and a complexing agent chelating the metal oxide oxidized by the oxidant.
Since severe surface defects such as erosion and dishing occur in the process of polishing a metal layer, particularly a copper (Cu) layer, using a CMP slurry composition as compared with other metals, the corrosion inhibitor and the complexing agent are introduced.
As such, in the process of polishing the metal layer, particularly, the copper layer, it is necessary to secure a low level of surface defects along with an appropriate polishing rate. Otherwise, a polishing time becomes longer or surface defects can occur.